1. Field of the Invention
The invention relates to multicast streams in a communications network, including Internet Protocol (IP) multicast streams. More particularly, the invention relates to provisioning multicast streams for use by headends or cores within communications networks.
2. Description of the Related Art
Due to the transmission of multiple versions of video content (e.g., national, regional and local) over networks, such as Internet Protocol (IP) transport networks, the number of video streams within the distribution portions of those transport networks is expanding. Typically, national feeds of video content are transmitted as multicast (MC) streams across a network backbone to regional and local hubs, also referred to as headends. At the regional and local headends, advertisement insertion requirements result in many regional and local versions of essentially the same video stream. The number of video streams is increased further by redundant copies of the video streams.
To receive a video stream of interest at the headend, the headend operator has to know several parameters about the video stream, including the multicast address (MCA), e.g., the IP multicast address (IP MCA), for the destination. The operator also has to know at least the user datagram protocol (UDP) port for the destination, and the Moving Picture Experts Group (MPEG) service number. Because several different video streams are received at the headend, the careful management, coordination and tracking of MCAs is necessary, as well as the efficient provisioning of devices in the distribution network.
Conventionally, the provisioning of video streams in devices is performed manually. However, manual provisioning of devices typically is inconvenient, and it also increases the likelihood of operator entry errors. Also, any changes to the video stream (e.g., transmit address changes) require the operator to make manual adjustments at each affected device.
Several conventional network protocols exist to provision network devices. The Domain Name System (DNS), a distributed Internet directory service that translates domain names into IP addresses, provides some provisioning, mainly for unicast addresses of hosts. However, DNS does not have a provision for providing the UDP port number and other desirable attributes of video stream content. Thus, DNS is not suitable for use with multicast video content and their systems.
Session Announcement Protocol (SAP), which is used to advertise multicast streams, typically contains within it a Session Description Protocol (SDP) payload, which describes multimedia sessions. However, as a broadcast protocol with a low repetition rate, SAP does not provide the on-demand provisioning service that devices throughout video distribution networks require. Moreover, if the SAP repetition rate is increased, the volume of data transmitted would overwhelm the network. SDP contains relevant information, but does not provide all the information devices may require in video stream descriptors. Moreover, SDP is not extensible to add information that may be required, either at present or in the future.